1. Field of the Disclosure
The present disclosure relates to a touch pad input device including a touch pad capable of sensing a touch or proximity of an operating object on or to an operation surface and a sensing unit capable of sensing a pressing operation on the touch pad.
2. Description of the Related Art
Touch pad input devices each including a touch pad capable of sensing a touch or proximity of an operating object on or to an operation surface and a sensing unit capable of sensing a pressing operation on the touch pad are currently in practical use. A touch pad input device is mounted at a predetermined position (palm rest or the like) in a housing of an electronic apparatus, such as a laptop computer, and is used to, for example, move a cursor on a screen.
Examples of related-art touch pad input devices include a three-dimensional data input device (touch pad input device) disclosed in Japanese Unexamined Patent Application Publication No. 2007-299043 and an input device (touch pad input device) disclosed in Japanese Unexamined Patent Application Publication No. 2013-164699. FIG. 12 is a diagram illustrating the configuration of a three-dimensional data input device 300 disclosed in Japanese Unexamined Patent Application Publication No. 2007-299043. FIG. 13 is a diagram illustrating the configuration of an input device 400 disclosed in Japanese Unexamined Patent Application Publication No. 2013-164699.
As illustrated in FIG. 12, the three-dimensional data input device 300 includes a rectangular touch panel (touch pad) 301 disposed above a substrate 306, two press borders 303 to be pressed, a support mechanism 304 for supporting the touch panel 301, and two contact pairs 305 corresponding one-to-one to the two press borders 303.
The touch panel 301 is a resistive, capacitive, or optical touch pad to input two-dimensional position data. The touch panel 301 includes a rotating shaft 302 in its rectangular central part and is rotatable about the rotating shaft 302, serving as a fulcrum. The two press borders 303 are arranged in both side portions of the touch panel 301. The support mechanism 304 includes two elastic members arranged between the touch panel 301 and the substrate 306. The support mechanism 304 keeps the touch panel 301 in a horizontal position under no pressure.
The two contact pairs 305 are arranged under and near the two press borders 303. When the touch panel 301 is rotated, one pair of the two contact pairs 305 is activated to output a contact signal indicating a rotating direction. The three-dimensional data input device 300 detects two-dimensional position data (indicating the position of an operating object in contact with or in proximity to an operation surface) based on an output of the touch panel 301 and detects three-dimensional direction data (pressing operation) based on an output of either of the two contact pairs 305.
As illustrated in FIG. 13, the input device 400 includes a panel 402, serving as a portion of a housing of a personal computer or the like, an operation substrate 410 located within an opening 403 of the panel 402, and a support structure portion 440a for supporting the operation substrate 410 with a lower surface of the panel 402.
The operation substrate 410 is a capacitive touch pad. The operation substrate 410 includes a metal plate (not illustrated), a sensor substrate (not illustrated) stacked on the metal plate, and a cover sheet 415 stacked on the sensor substrate. The cover sheet 415 has a surface, serving as an operation surface 415a. A pressing force sensor (not illustrated) is disposed under the operation substrate 410. In the input device 400, the operation substrate 410 senses a touch or proximity of an operating object, such as a finger, on or to the operation substrate 410 and the pressing force sensor senses a pressing force applied to the operation substrate 410.
The support structure portion 440a includes a support portion 404 included in the lower surface of the panel 402, a connection portion 424a provided for an end of the operation substrate 410, an elastic body 441 retained by the connection portion 424a, and a retaining member 442 for screwing. The support portion 404 is a flat portion included in the lower surface of the panel 402 and is parallel to a front surface 402a of the panel 402. The support portion 404 has an internally-threaded hole 405 and includes a positioning projection 406 and a stopper projection 407.
The connection portion 424a extends outwardly from a step portion 423a provided at the end of the operation substrate 410. The connection portion 424a has a retaining hole 427a and a positioning hole 428a. The connection portion 424a has an opposing region 407a in its upper surface. The opposing region 407a faces the stopper projection 407.
The elastic body 441 includes an upper elastic portion 441b and a lower elastic portion 441c and has a through hole 441d extending through central part of the elastic body 441, a retaining groove 441a disposed between the upper elastic portion 441b and the lower elastic portion 441c, and a cross-shaped groove 441e in the upper elastic portion 441b. The retaining member 442 includes a disk-shaped facing member 442a and has a lower surface 442e with a fit groove to which a screwdriver is to be fitted. The retaining member 442 further includes a shaft portion 442b extending upwardly from the facing member 442a, a step portion 442c, serving as an upper end of the shaft portion 442b, and an externally-threaded portion 442d. 
The elastic body 441 is retained in the retaining hole 427a of the connection portion 424a, the shaft portion 442b of the retaining member 442 is inserted into the through hole 441d of the elastic body 441, and the externally-threaded portion 442d is threaded into the internally-threaded hole 405 of the panel 402, thus urging the operation substrate 410 upward. Upwardly urging the operation substrate 410 enables the operation substrate 410 to be retained.
In such a touch pad input device, the touch pad has to be securely retained so as not to be detached from the housing of the electronic apparatus when the touch pad is pressed. With the modern trend toward smaller electronic apparatuses, such as laptop computers, there has been an increasing demand for smaller footprints of touch pad input devices mounted in the electronic apparatuses.
Japanese Unexamined Patent Application Publication No. 2007-299043 discloses a method of supporting the touch panel 301 of the three-dimensional data input device 300 such that the touch panel 301 can be pressed. However, there is no mention of any method of retaining the touch panel 301 so as not to detach the touch panel 301 from the substrate.
In the input device 400 disclosed in Japanese Unexamined Patent Application Publication No. 2013-164699, the connection portion 424a of the operation substrate 410 is screwed on the panel 402, with the elastic body 441 therebetween. Consequently, the operation substrate 410 is supported such that the operation substrate 410 can be pressed. Additionally, the operation substrate 410 is securely retained so as not to be detached from the panel 402 when the operation substrate 410 is pressed.
In the input device 400, the operation substrate 410 is urged upward. To urge the operation substrate 410 upward, the connection portion 424a has to be deviated from the operation substrate 410 so as to avoid the operation surface when viewed from above. This leads to an increased footprint of the input device 400. This interferes with miniaturization of an electronic apparatus in which the input device 400 is mounted.